Remove priority and weight from panel groups and panels

What does this MR do?

Replacement MR for gitlab-foss!31536 (closed)

Remove sorting of panels and groups by priority and weight. This allows the groups and panels to appear in the order they are mentioned in the *_metrics.yml files.

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

Customers that have built dashboards relying on weight and priority will be surprised if the order of their panels and dashboards change. Additionally, customers will not be able to reference the previous order once this code has been deployed.

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers

Security